Scientists Find Possibility of Nitrogen-Fixing Corn

The dripping gel from this corn plant harbors bacteria that convert atmospheric nitrogen into a form usable by the plant.
( HOWARD-YANA SHAPIRO )

At a towering 16’ tall, corn native to Oaxaca, Mexico grows up to 10 aerial roots [compared to two in a typical plant] that secrete gel to help nitrogen-fixing bacteria survive. If scientists find a way to make this commercially available, it could be a game-changer for corn grown for grain and silage.

The corn has been tested in Mexico and Madison, Wisconsin. The gel secreted by aerial roots allows corn to fix nitrogen by excluding oxygen and providing sugars to the ‘right’ bacteria, according to a recent University of Wisconsin press release.

“It took us eight years of work to convince ourselves that this was not an artifact,” said Jean-Michel Ané, professor of bacteriology and agronomy and University of Wisconsin-Madison and co-author of the study. “Technique after technique, they’re all giving the same result showing high levels of nitrogen fixation in this corn.

“What I think is cool about this project is it completely turns upside down the way we think about engineering nitrogen fixation,” Ané added.

Corn with this capability can acquire 30% to 80% of the nitrogen it needs through fixation. Humidity and rain control just how much or little nitrogen the plant gains. More research is needed to determine if this trait can be bred into commercial corn cultivars.

Found in the Sierra Mixe region of southern Mexico, soil is nitrogen-depleted, and farmers use little to no fertilizer. These conditions have selected for corn’s ability to acquire nitrogen. Researchers used five different techniques to confirm the corn gel is in fact fixing nitrogen from the air that the corn can incorporate into its own tissue.

“This corn showed us that nature can find solutions to some problems far beyond what scientists could ever imagine,” Ané said. “The scientific community probably underestimated nitrogen fixation in other crops because of its obsession with root nodules.”

This research is a collaboration between University of Wisconsin-Madison, University of California, Davis and Mars, Inc.